OAA computing section circular NK 684 P/1987 Q3 (Helin)

The following improved orbital elements, by S. Nakano, are from 25 observations 1987 Aug. 24-1988 Feb. 13. Perturbations by Mercury to Neptune and three minor planets, Ceres, Pallas and Vesta, were taken into account. The mean residual is +/- 1.17 arc seconds. Epoch = 1987 July 24.0 TT T = 1987 Aug. 12.13605 +/- 0.03467 (m.e.) TT Peri. = 216.25518 +/- 0.01251 Node = 143.73426 +/- 0.00231 (2000.0) Inc. = 4.68685 +/- 0.00013 q = 2.5712436 +/- 0.0001280 AU e = 0.5666935 +/- 0.0000346 a = 5.9340065 +/- 0.0000941 AU n' = 0.06818393 +/- 0.00000162 P = 14.455 +/- 0.0003439 years (+/- 0.13 day) The predicted orbit for the 2001 return is as follows: T = 2001 Sept.26.44792 TT Epoch = 2001 Sept. 8.0 TT Peri. = 215.40697 e = 0.5657640 Node = 143.53757 (2000.0) a = 5.8279606 AU Inc. = 4.71718 n'= 0.07005339 q = 2.5307100 AU P = 14.069 years The following residuals in seconds of arc are from the above orbital elements: 1987/ 870922 688 0.7+ 1.0+ 871222 691 0.7+ 0.4+ 870824 675 2.2- 0.7- 870927 691 1.2+ 0.4+ 1988/ 870824 675 2.3- 0.4+ 870927 691 1.6+ 0.1- 880115 691 0.4- 0.5- 870826 675 2.6- 0.4- 870927 691 1.2+ 0.5+ 880115 691 (2.9- 0.5-) 870826 675 (3.1- 0.2+) 870927 691 1.2+ 0.4+ 880115 688 0.4- 1.3- 870917 675 0.6+ 1.4- 871016 691 0.2- 0.5+ 880115 688 0.9- 1.0- 870917 675 (4.5+ 1.4+) 871016 691 0.6- 0.4+ 880121 691 2.2- 0.6- 870918 675 1.5+ 0.1- 871026 688 0.9- 2.1- 880121 691 (5.0- 0.1-) 870918 675 (2.8+ 0.7+) 871026 688 1.0- 2.1- 880212 691 0.8- 1.6+ 870922 688 0.7+ 1.3+ 871221 691 (2.8- 1.5-) 880212 691 1.5+ 0.3+ 870922 688 0.8+ 1.3+ 871222 691 1.7+ 1.4+ 880213 691 0.7- 0.9+ ( ) -------- Rejected Obs.

Director, Computing Section Syuichi Nakano 1998 May 2

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